NONDISRUPTIVE, IN-VIVO METHOD FOR BIOMECHANICAL CHARACTERIZATION OF LINEAR INCISION WOUND-HEALING - PRELIMINARY-REPORT

Previous work on in vivo biomechanical characterization of soft tissue s and wound healing has led to the development of a methodology for no ndisruptive, in vivo biomechanical analysis of linear incision wounds. The purpose of this preliminary study was to define nondisruptive bio mechanical parameters that characterize progressive healing and compar e them with an in vivo disruptive parameter of ultimate pressure at fa ilure tin vivo strength). Male Sprague-Dawley rats (n = 60), each weig h ing 250 to 300 gm, were anesthetized and underwent creation of paire d full-thickness linear incision wounds. The rats were divided into th ree groups (n = 10/group per time period): control group, nothing appl ied to either wound; carrier group, bovine serum albumin applied to ea ch wound; transforming growth factor-beta 2 group, transforming growth factor-beta 2 in bovine serum albumin applied to each wound. On posto perative days 5 and 10, rats from each group underwent in vivo biomech anical testing using the Dimensional Analysis System (Dimensional Anal ysis Systems, Inc., Nashville, Tenn.). This computer driven device int egrates a video camera and processor with a vacuum controller, valve, and transducer to provide measurements of tissue deformation tin milli meters) and negative pressure (mmHg) as a multiaxial stress (vacuum) i s applied to a wound. On each rat, one incision was tested disruptivel y and the other incision was tested nondisruptively. Disruptive data w ere measured as ultimate pressure (mmHg) at failure, or the amount of pressure required to disrupt the wound. Nondisruptive data were measur ed for tissue stiffness (kiloPascals) during application of negative p ressure (maximum, 80 mmHg). On postoperative day 5, wounds treated wit h transforming growth factor-beta 2 had significantly increased in viv o wound strength compared with carrier wounds. The nondisruptive param eter of tissue stiffness was also significantly increased for the tran sforming growth factor-beta 2 treated wounds, thus supporting the disr uptive data. On postoperative day 10, there was no difference in mean wound strength or mean tissue stiffness among any of the groups. These preliminary data represent the fir st report of in vivo, nondisruptiv e biome chanical characterization of linear incision wounds. The resul ts suggest that through in vivo measurements of tissue stiffness, diff erences can be detected between treatment groups. Because the healing wound may be characterized without the need for disruption, this metho dology should allow for consecutive, in vivo biomechanical testing of wounds in future wound healing studies.